Coevolution and the origins of reproductive isolation

共同进化和生殖隔离的起源

• 批准号: RGPIN-2018-06462
• 负责人: Chippindale, Adam
• 金额: $ 4.81万
• 依托单位: Queen's University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=745648
• 关键词: Coevolution; origins; reproductive; isolation

Since Darwin, the predominant view of how new species arise is through adaptation occurring in isolated populations experiencing different ecological selection pressures. However there are “non-ecological” mechanisms by which reproductive isolation (RI) can evolve when populations are divided. Among these, it has been suggested that intersexual coevolution (IC) may be a particularly potent “engine of speciation”. IC occurs through reciprocal adaptation of one sex to features of the other sex in reproduction, cooperation or conflict between the sexes. Because IC is driven by open-ended cycles of adaptation and counter-adaptation within populations, isolated populations may diverge simply because, by chance, new favourable mutations arising in one population are different from those arising in another. RI arising through such a process has been called mutation order divergence (MOD). There are few convincing tests of the MOD hypothesis because separated natural populations inevitably have ecological differences to one degree or another, often have unknown histories, and may be difficult to experiment with.I will take advantage of a powerful long-term evolution experiment with the fruit fly, Drosophila, to quantify mechanisms contributing to the early stages of speciation. Numerous studies with this species have shown that IC is measureable over time scales of 10's of generations. My 15-population experiment has been running for over 25y and has populations isolated from common ancestry for as many as 2,600 generations, evolved under 3 different treatments. Populations from each treatment have markedly different characteristics, especially related to body size, development and age of reproduction, constituting a source of ecological divergence. Populations in the same treatment have identical handling histories but are genetically isolated, as if occupying separate islands with identical ecology. Pilot studies show considerable pre-mating isolation has evolved between populations selected for different characteristics, like preferring like in mate choice, and some physical mating incompatibilities between them. Future research will expand this work on mate choice, look at post-mating pre-fertilization competition between sperm, fertilization success, and the success of first- and second-generation hybrids between populations. With perhaps the longest running evolution experiment undertaken in an animal species, control over the environment, knowledge of the genome of the species and the specific populations being used, and near perfect knowledge of the history of the lines since domestication, we have an opportunity to characterize the nature of evolving reproductive isolation in unprecedented detail.

自达尔文以来，关于新物种如何产生的主流观点是通过在经历不同生态选择压力的孤立种群中发生的适应。然而，有“非生态”的机制，生殖隔离（RI）可以演变时，种群的分裂。其中，有人建议，间性共同进化（IC）可能是一个特别强大的“物种形成引擎”。IC通过一种性别对另一种性别的特征在生殖、合作或冲突中的相互适应而发生。由于IC是由种群内的适应和反适应的开放式循环驱动的，孤立的种群可能仅仅因为一个种群中出现的新的有利突变与另一个种群中出现的突变不同而产生分歧。通过这种过程产生的RI被称为突变顺序发散（MOD）。对于MOD假说，目前还没有令人信服的检验方法，因为分离的自然种群不可避免地存在着不同程度的生态差异，它们往往有着未知的历史，而且可能很难进行实验。我将利用果蝇的一个强大的长期进化实验，来量化促成物种形成早期阶段的机制。对该物种的许多研究表明，IC可以在10代的时间尺度上测量。我的15个种群的实验已经运行了25年多，并且已经从共同祖先中分离了多达2,600代的种群，在3种不同的处理下进化。每个处理的种群具有明显不同的特征，特别是与体型、发育和繁殖年龄有关的特征，构成了生态差异的来源。在相同的处理中，种群有相同的处理历史，但在遗传上是孤立的，就好像占据了具有相同生态的独立岛屿。初步研究表明，相当大的交配前隔离已经演变为不同的特征，如喜欢在配偶选择，和一些物理交配之间的不兼容性选择的种群之间。未来的研究将扩大这项工作的配偶选择，看看交配后受精前精子之间的竞争，受精成功，以及第一代和第二代杂交种群之间的成功。也许是在动物物种中进行的时间最长的进化实验，对环境的控制，物种基因组的知识和所使用的特定种群，以及对驯化以来品系历史的近乎完美的了解，我们有机会以前所未有的细节来描述进化生殖隔离的性质。